Liquid crystal composition and liquid crystal display device

ABSTRACT

Subject The subject is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or that is suitably balanced regarding two or more characteristics. The subject is to provide an AM device that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. 
     Means for Solving the Subject The invention provides a liquid crystal composition that has a nematic phase and includes a specific four-ring compound having a high maximum temperature as a first component, a compound having a specific bonding group and a large dielectric anisotropy as a second component, and a specific two-ring compound having a small viscosity as a third component, and provides a liquid crystal display device containing the composition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device, and an AM device containing thecomposition. More specifically, the invention relates to a liquidcrystal composition having a positive dielectric anisotropy, and adevice containing the composition and having a mode such as twistednematic, optically compensated bend, in-plane switching or polymersustained alignment.

2. Related Art

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes phase change (PC), twistednematic (TN), super twisted nematic (STN), electrically controlledbirefringence (ECB), optically compensated bend (OCB), in-planeswitching (IPS), vertical alignment (VA) and polymer sustained alignment(PSA). A classification based on a driving mode in the device includes apassive matrix (PM) and an active matrix (AM). The PM is furtherclassified into static, multiplex and so forth, and the AM is classifiedinto a thin film transistor (TFT), a metal-insulator-metal (MIM) and soforth. The TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to the production process. Aclassification based on a light source includes a reflection typeutilizing natural light, a transmission type utilizing a backlight and asemi-transmission type utilizing both natural light and a backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be further explainedbased on a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or higher and a desirable minimum temperature ofthe nematic phase is approximately −10° C. or lower. The viscosity ofthe composition relates to the response time of the device. A shortresponse time is desirable to display moving images on the device.Accordingly, a small viscosity of the composition is desirable. A smallviscosity at a low temperature is more desirable.

TABLE 1 General Characteristics of Composition and AM Device No. GeneralCharacteristics of Composition General Characteristics of AM Device 1wide temperature range of a nematic phase wide usable temperature range2 small viscosity¹⁾ short response time 3 suitable optical anisotropylarge contrast ratio 4 positively or negatively large dielectric lowthreshold voltage and small electric anisotropy power consumption largecontrast ratio 5 large specific resistance large voltage holding ratioand large contrast ratio 6 high stability to ultraviolet light and heatlong service life ¹⁾A liquid crystal composition can be injected into aliquid crystal cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kinds of operating modes. In a device having a TN mode, a suitablevalue is about 0.45 micrometer. In this case, a composition having alarge optical anisotropy is desirable for a device having a small cellgap. A large dielectric anisotropy of the composition contributes to alow threshold voltage, a low electric power consumption and a largecontrast ratio of the device. Accordingly, a large dielectric anisotropyis desirable. A large specific resistance of the composition contributesto a large voltage holding ratio and a large contrast ratio of thedevice. Accordingly, a composition having a large specific resistance isdesirable at room temperature and also at a high temperature in theinitial stage. A composition having a large specific resistance isdesirable at room temperature and also at a high temperature after ithas been used for a long time. The stability of the composition toultraviolet light and heat relates to the service life of the liquidcrystal display device. In the case where the stability is high, thedevice has a long service life. These characteristics are desirable foran AM device used in a liquid crystal projector, a liquid crystaltelevision and so forth.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device having a PSAmode. Examples of the liquid crystal composition having positivedielectric anisotropy are disclosed in the following patent documentNo. 1. The compound of a first component is described in the patentdocument No. 2.

No. 1: JP 2002-533526 A (2002) and No. 2 JP 2000-328060 A (2000).

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time is desirably shorter even by onemillisecond. Thus, a composition having characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of anematic phase, a small viscosity, a large optical anisotropy, a largedielectric anisotropy, a large specific resistance, a high stability toultraviolet light and a high stability to heat is especially desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition that has a nematicphase and includes three components, wherein a first component is atleast one compound selected from the group of compounds represented byformula (1), a second component is at least one compound selected fromthe group of compounds represented by formula (2), and a third componentis at least one compound selected from the group of compoundsrepresented by formula (3), and concerns also a liquid crystal displaydevice containing this composition:

wherein R¹, R² and R³ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁵ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine; one of X¹ and X² is fluorine andthe other is hydrogen; the ring A and the ring B are each independently

the ring C and the ring D are each independently

and m is 0, 1 or 2.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and the liquid crystal display device ofthe invention may occasionally be abbreviated to “the composition” and“the device,” respectively. A liquid crystal display device is a genericterm for a liquid crystal display panel and a liquid crystal displaymodule. The “liquid crystal compound” is a generic term for a compoundhaving a liquid crystal phase such as a nematic phase and a smecticphase, and also for a compound having no liquid crystal phases but beinguseful as a component of a composition. The useful compound has asix-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, and arod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystal compounds, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) mayoccasionally be abbreviated to “the compound (1).” “The compound (1)”means one compound, or two or more compounds represented by formula (1).The same rules apply to compounds represented by the other formulas. Thecompound (1-1) and the compound (1-2) are lumped together and may beexpressed as the compound (1), and the compound (2-1-1), the compound(2-2-1), the compound (2-2-2), the compound (2-3-1), the compound(2-3-2) and so forth are lumped together and may be expressed as thecompound (2). “Arbitrary” is used not only in cases when the position isarbitrary but also in cases when the number is arbitrary. However, it isnot used in cases when the number is 0 (zero).

A higher limit of the temperature range of a nematic phase mayoccasionally be abbreviated to “the maximum temperature.” A lower limitof the temperature range of a nematic phase may occasionally beabbreviated to “the minimum temperature.” That “specific resistance islarge” means that a composition has a large specific resistance at roomtemperature and also at a temperature close to the maximum temperatureof a nematic phase in the initial stage, and that the composition has alarge specific resistance at room temperature and also at a temperatureclose to the maximum temperature of a nematic phase even after it hasbeen used for a long time. That “a voltage holding ratio is large” meansthat a device has a large voltage holding ratio at room temperature andalso at a temperature close to the maximum temperature of a nematicphase in the initial stage, and that the device has a large voltageholding ratio at room temperature and also at a temperature close to themaximum temperature of a nematic phase even after it has been used for along time. When characteristics such as optical anisotropy areexplained, values which are obtained according to the measuring methodsdescribed in Examples will be used. A first component means onecompound, or two or more compounds. “The ratio of the first component”is expressed in a percentage by weight (% by weight) of the firstcomponent based on the total weight of the liquid crystal composition.The same rule applies to the ratio of a second component and so forth. Aratio of an additive mixed with the composition is expressed in apercentage by weight (% by weight) or weight parts per million (ppm)based on the total weight of the liquid crystal composition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. The meanings of R¹ may be identical ordifferent in two arbitrary compounds among these. In one case, forexample, R¹ of the compound (1-1) is ethyl and R¹ of the compound (1-2)is ethyl. In another case, R¹ of the compound (1-1) is ethyl and R¹ ofthe compound (1-2) is propyl. The same rule applies to the symbols R²,R³ and so forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Anotheradvantage of the invention is to provide a liquid crystal compositionthat is suitably balanced regarding at least two of the characteristics.A further advantage of the invention is to provide a liquid crystaldisplay device that contains the liquid crystal composition. Anadditional advantage of the invention is to provide a liquid crystalcomposition that has a suitable optical anisotropy, a large dielectricanisotropy, a high stability to ultraviolet light and so forth, and isto provide an AM device that has a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

The liquid crystal composition of the invention satisfied at least oneof characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a suitable optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light and a highstability to heat. The liquid crystal composition was suitably balancedregarding at least two of the characteristics. The liquid crystaldisplay device contained the liquid crystal composition. The liquidcrystal composition had a suitable optical anisotropy, a largedielectric anisotropy, a high stability to ultraviolet light and soforth, and the AM device had a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

The invention includes the following items.

Item 1. A liquid crystal composition that has a nematic phase andincludes three components, wherein a first component is at least onecompound selected from the group of compounds represented by formula(1), a second component is at least one compound selected from the groupof compounds represented by formula (2), and a third component is atleast one compound selected from the group of compounds represented byformula (3):

wherein R¹, R² and R³ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁵ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine; one of X¹ and X² is fluorine andthe other is hydrogen; the ring A and the ring B are each independently

the ring C and the ring D are each independently

and m is 0, 1 or 2.Item 2. The liquid crystal composition according to item 1, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-1):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.Item 3. The liquid crystal composition according to item 1 or 2, whereinthe second component is at least one compound selected from the group ofcompounds represented by formula (2-1-1), formula (2-2-1), formula(2-2-2), formula (2-3-1) and formula (2-3-2):

wherein R³ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.Item 4. The liquid crystal composition according to any one of items 1to 3, wherein the third component is at least one compound selected fromthe group of compounds represented by formula (3-1), formula (3-2) andformula (3-3):

wherein R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁵ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine.Item 5. The liquid crystal composition according to item 4, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).Item 6. The liquid crystal composition according to any one of items 1to 5, wherein the ratio of the first component is in the range ofapproximately 5% to approximately 30% by weight, the ratio of the secondcomponent is in the range of approximately 5% to approximately 50% byweight, and the ratio of the third component is in the range ofapproximately 5% to approximately 50% by weight, based on the totalweight of the liquid crystal composition.Item 7. The liquid crystal composition according to any one of items 1to 6, further including at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; Z¹ and Z² are eachindependently a single bond, ethylene or carbonyloxy; the ring E and thering F are each independently

and n is 1 or 2.Item 8. The liquid crystal composition according to item 7, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-1) to formula (4-9):

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.Item 9. The liquid crystal composition according to any one of items 1to 8, further including at least one compound selected from the group ofcompounds represented by formula (5) as a fifth component:

wherein R⁷ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁸ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine; Z³ and Z⁴ are each independently asingle bond, ethylene, carbonyloxy, methyleneoxy or oxymethylene; thering G, the ring H and the ring I are each independently

and p is 1 or 2.Item 10. The liquid crystal composition according to item 9, wherein thefifth component is at least one compound selected from the group ofcompounds represented by formula (5-1) to formula (5-9):

wherein, R⁷ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁸ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine.Item 11. The liquid crystal composition according to any one of items 1to 10, wherein the ratio of the first component is in the range ofapproximately 5% to approximately 30% by weight, the ratio of the secondcomponent is in the range of approximately 15% to approximately 45% byweight, the ratio of the third component is in the range ofapproximately 10% to approximately 40% by weight, the ratio of thefourth component is in the range of 0% to approximately 50% by weight,and the ratio of the fifth component is in the range of 0% toapproximately 30% by weight, based on the total weight of the liquidcrystal composition.Item 12. A liquid crystal display device including the liquid crystalcomposition according to any one of items 1 to 11.Item 13. The liquid crystal display device according to item 12, whereinan operating mode of the liquid crystal display device is a TN mode, anECB mode, an OCB mode, an IPS mode or a PSA mode, and a driving mode ofthe liquid crystal display device is an active matrix mode.

The invention further includes the following items: (1) the compositiondescribed above that further includes an optically active compound; (2)the composition described above that further includes an additive, suchas an antioxidant, an ultraviolet light absorbent, an antifoaming agent,a polymerizable compound and/or a polymerization initiator; (3) an AMdevice that contains the composition described above; (4) a devicehaving a mode of TN, ECB, OCB, IPS, VA or PSA and containing thecomposition described above; (5) a device having a transmission type andcontaining the composition described above; (6) use of the compositiondescribed above as a composition having a nematic phase; and (7) use ofthe composition described above as an optically active composition byadding an optically active compound to the composition.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of the compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, examples of the component compounds will beshown. Sixth, additives that may be mixed with the composition will beexplained. Seventh, methods for synthesizing the component compoundswill be explained. Last, use of the composition will be explained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. In addition to the compound (1),the compound (2), the compound (3), the compound (4) and/or the compound(5), the composition A may include any other liquid crystal compound, anadditive and an impurity. “Any other liquid crystal compound” isdifferent from the compound (1), the compound (2), the compound (3), thecompound (4) and the compound (5). Such a compound is mixed with thecomposition for the purpose of further adjusting characteristics of thecomposition. Of any other liquid crystal compound, a smaller amount of acyano compound is more desirable in view of its stability to heat orultraviolet light. A more desirable ratio of the cyano compound is 0% byweight. The additive includes an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The impurity is a compound and so forth which contaminatedthe component compounds in a process such as their synthesis. Even inthe case where the compound is liquid crystalline, it is classified asan impurity herein.

The composition B is essentially consisting of compounds selected fromthe group of the compound (1), the compound (2), the compound (3), thecompound (4) and the compound (5). The term “essentially” means that thecomposition may include an additive and an impurity, but does notinclude any liquid crystal compound other than these compounds. Thecomposition B has a smaller number of components than the composition A.The composition B is preferable to the composition A in view of costreduction. The composition A is preferable to the composition B in viewof the fact that physical properties can be further adjusted by addingany other liquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2 onthe basis of the effects of the invention. In Table 2, the symbol Lstands for “large” or “high”, the symbol M stands for “medium”, and thesymbol S stands for “small” or “low.” The symbols L, M and S areclassified on the basis of a qualitative comparison among the componentcompounds, and 0 (zero) means that “a value is nearly zero.”

TABLE 2 Characteristics of Compounds Compounds (2) (2-1) (2-2) (2-3) (3)(4) (5) Maximum L S S-M M S M M-L Temperature Viscosity M M-L M-L M-L SL M Optical M S-M S-M M S-M S-M S-L Anisotropy Dielectric 0 L L L 0 L 0Anisotropy Specific L L L L L L L Resistance

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) increases the maximum temperature anddecreases the viscosity. The compound (2) increases the dielectricanisotropy. The compound (3) decreases the minimum temperature anddecreases the viscosity. The compound (4) increases the dielectricanisotropy. The compound (5) increases the maximum temperature.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. The combination of the components in the composition is thefirst, second and third components, the first, second, third and forthcomponents, the first, second, third and fifth components, and thefirst, second, third, forth and fifth components.

A desirable ratio of the first component is approximately 5% by weightor more for increasing the maxim temperature or for decreasing theviscosity, and is approximately 30% by weight or less for decreasing theminimum temperature. A more desirable ratio is in the range ofapproximately 5% to approximately 25% by weight. An especially desirableratio is in the range of approximately 5% to approximately 20% byweight.

A desirable ratio of the second component is approximately 5% by weightor more for increasing the dielectric anisotropy, and is approximately50% by weight or less for decreasing the viscosity. A more desirableratio is in the range of approximately 15% to approximately 45% byweight. An especially desirable ratio is in the range of approximately15% to approximately 40% by weight.

A desirable ratio of the third component is approximately 5% by weightor more for decreasing the viscosity, and is approximately 50% by weightor less for decreasing the minimum temperature. A more desirable ratiois in the range of approximately 10% to approximately 40% by weight. Anespecially desirable ratio is in the range of approximately 10% toapproximately 35% by weight.

A desirable ratio of the fourth component is 0% by weight or more forincreasing the dielectric anisotropy, and is approximately 50% by weightor less for decreasing the minimum temperature. A more desirable ratiois in the range of approximately 5% to approximately 40% by weight. Anespecially desirable ratio is in the range of approximately 15% toapproximately 40% by weight.

A desirable ratio of the fifth component is 0% by weight or more forincreasing the maximum temperature or for decreasing the viscosity, andis approximately 30% by weight or less for decreasing the minimumtemperature. A more desirable ratio is in the range of approximately 5%to approximately 25% by weight. An especially desirable ratio is in therange of approximately 10% to approximately 20% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained.

R¹, R², R³ and R⁶ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.Desirable R¹, R², R³ or R⁶ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat.

R⁴ and R⁷ are each independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine. Desirable R⁴ or R⁷ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat, alkenyl having 2to 12 carbons for decreasing the minimum temperature or for decreasingthe viscosity, and alkenyl having 2 to 12 carbons in which arbitraryhydrogen is replaced by fluorine or alkoxy having 1 to 12 carbons forincreasing the dielectric anisotropy.

R⁵ and R⁸ are each independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, fluorine orchlorine. Desirable R⁵ or R⁸ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat, alkenyl having 2to 12 carbons for decreasing the minimum temperature or for decreasingthe viscosity, and alkoxy having 1 to 12 carbons, fluorine or chlorinefor increasing the dielectric anisotropy.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. A more desirable alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. A more desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Amore desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity and for something. C ispreferable in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.In the alkenyl, straight-chain alkenyl is preferable to branched-chainalkenyl.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The ring A, the ring B, the ring E and the ring F are each independently1,4-cyclohexylene, 1,4-phenylene, 3-fluoro-1,4-phenylene,3,5-difluoro-1,4-phenylene, 2-pyran-2,5-diyl, 1,3-dioxane-2,5-diyl,2,5-pyridine and 2,5-pyrimidine; and two of the ring A may be identicalor different when m is 2 and two of the ring E may be identical ordifferent when n is 2. Desirable ring A, ring B, ring E or ring F is1,4-cyclohexylene for decreasing the viscosity, 1,4-phenylene forincreasing the optical anisotropy, and 3-fluoro-1,4-phenylene,3,5-difluoro-1,4-phenylene, 1,3-dioxane-2,5-diyl or 2,5-pyrimidine forincreasing the dielectric anisotropy.

The ring C, the ring D, the ring G, the ring H and the ring I are eachindependently 1,4-cyclohexylene, 1,4-phenylene or3-fluoro-1,4-phenylene, and two of the ring E may be identical ordifferent when p is 2. Desirable ring C, ring D, ring G, ring H or ringI is 1,4-cyclohexylene for decreasing the viscosity and 1,4-phenylene or3-fluoro-1,4-phenylene for increasing the optical anisotropy.

One of X¹ and X² is fluorine and the other is hydrogen. X² is hydrogenwhen X¹ is fluorine and X² is fluorine when X¹ is hydrogen. In adesirable combination of X¹ and X², X¹ is fluorine and X² is hydrogenfor decreasing the minimum temperature.

Z¹ and Z² are each independently a single bond, ethylene or carbonyloxy.Desirable Z¹ or Z² is a single bond or ethylene for decreasing theviscosity and carbonyloxy for increasing the dielectric anisotropy. Z³and Z⁴ are each independently a single bond, ethylene, carbonyloxy,methyleneoxy or oxymethylene. Desirable Z³ or Z⁴ is a single bond fordecreasing the viscosity.

m is 0, 1 or 2. Desirable m is 1 or 2 for increasing the maximumtemperature, and is 0 for decreasing the minimum temperature. n is 1 or2. Desirable n is 2 for increasing the maximum temperature, and is 1 fordecreasing the minimum temperature. p is 1 or 2. Desirable p is 2 forincreasing the maximum temperature, and is 1 for decreasing theviscosity.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R¹, R², R³ and R⁶ are eachindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons, R⁴ and R⁷ are eachindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine, and R⁵ andR⁸ are each independently alkyl having 1 to 12 carbons, alkoxy having 1to 12 carbons, alkenyl having 2 to 12 carbons, fluorine or chlorine.With regard to the configuration of 1,4-cyclohexylene in thesecompounds, trans is preferable to cis for increasing the maximumtemperature.

Desirable compound (1) are the compounds (1-1) and (1-2). More desirablecompound (1) is the compound (1-1) Desirable compound (2) are thecompounds (2-1-1), (2-1-2), (2-2-1), (2-2-2), (2-2-3), (2-2-4), (2-3-1),(2-3-2), (2-3-3) and (2-3-4). More desirable compound (2) are thecompounds (2-1-1), (2-2-1), (2-2-2), (2-3-1) and (2-3-2). Especiallydesirable compound (2) are the compounds (2-2-1), (2-2-2), (2-3-1) and(2-3-2). Desirable compound (3) are the compounds (3-1), (3-2) and(3-3). More desirable compound (3) is the compound (3-1). Desirablecompound (4) are the compound (4-1) to the compound (4-15). Moredesirable compound (4) are the compound (4-1) to the compound (4-9).Especially desirable compound (4) are the compounds (4-1), (4-4) and(4-9). Desirable compound (5) are the compound (5-1) to the compound(5-9). More desirable compound (5) are the compounds (5-1), (5-6) and(5-8).

Sixth, additives which may be mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of the optically active compound includethe compound (6-1) to the compound (6-5) below. A desirable ratio of theoptically active compound is approximately 5% by weight or less, and amore desirable ratio is in the range of approximately 0.01% toapproximately 2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance caused by heating under air, or tomaintain a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of a nematic phase evenafter the device has been used for a long time.

Desirable examples of the antioxidant include the compound (7) where sis an integer of from 1 to 9. In the compound (7), desirable s is 1, 3,5, 7 or 9. More desirable s is 1 or 7. The compound (7) where s is 1 iseffective in preventing a decrease of the specific resistance caused byheating under air because it has a large volatility. The compound (7)where s is 7 is effective in maintaining a large voltage holding ratioat room temperature and also at a temperature close to the maximumtemperature of a nematic phase even after the device has been used for along time, because it has a small volatility. A desirable ratio of theantioxidant is approximately 50 ppm or more for achieving its effect andis approximately 600 ppm or less for avoiding a decrease of the maximumtemperature or avoiding an increase of the minimum temperature. A moredesirable ratio is in the range of approximately 100 ppm toapproximately 300 ppm.

Desirable examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorbentor the light stabilizer is approximately 50 ppm or more for achievingits effect and is approximately 10,000 ppm or less for avoiding adecrease of the maximum temperature or avoiding an increase of theminimum temperature. A more desirable ratio is in the range ofapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range ofapproximately 0.01% to approximately 10% by weight. An antifoaming agentsuch as dimethyl silicone oil or methyl phenyl silicone oil is mixedwith the composition for preventing foam formation. A desirable ratio ofthe antifoaming agent is approximately 1 ppm or more for achieving itseffect and is approximately 1,000 ppm or less for avoiding a poordisplay. A more desirable ratio is in the range of approximately 1 ppmto approximately 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a polymer sustained alignment (PSA) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound isapproximately 0.05% by weight or more for achieving its effect and isapproximately 10% by weight or less for avoiding a poor display. Amoredesirable ratio is in the range of approximately 0.1% to approximately2% by weight. The polymerizable compound is preferably polymerized onirradiation with ultraviolet light or the like in the presence of asuitable initiator such as a photopolymerization initiator. Suitableconditions for polymerization, suitable types of the initiator andsuitable amounts thereof are known to a person skilled in the art andare described in the literature. For example, Irgacure 651 (registeredtrademark), Irgacure 184 (registered trademark) or Darocure 1173(registered trademark) (Ciba Japan K.K.), each of which is aphotopolymerization initiator, is suitable for radical polymerization. Adesirable ratio of the photopolymerization initiator is preferably inthe range of approximately 0.1% to approximately 5% by weight, and mostpreferably in the range of approximately 1% to approximately 3% byweight based on the weight of the polymerizable compound.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be synthesized by known methods. Thesynthetic methods will be exemplified as follows. The compound (2-1-1)and the compound (2-2-1) are synthesized by the method described in JPH10-204016 A (1998). The compound (2-2-2) and the compound (2-3-1) aresynthesized by the method described in JP H10-251186 A (1998). Thecompound (3-1) is synthesized by the method described in JP 559-70624 A(1984), JP S59-176221 A (1984) and JP H01-175947 A (1989). The compound(4-1) and the compound (4-4) are synthesized by the method described inJP H02-233626 A (1990). The compound (5-6) is synthesized by the methoddescribed in JP 2006-503130A (2006). An antioxidant is commerciallyavailable. The compound of formula (7) where n is 1 is available fromSigma-Aldrich Corporation. The compound (7) where n is 7, and so forthare synthesized according to the method described in U.S. Pat. No.3,660,505.

Compounds whose synthetic methods are not described above can besynthesized according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanesetitle) (Maruzen Co., Ltd.). The composition is prepared according toknown methods using the compounds thus obtained. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, use of the composition will be explained. The composition mainlyhas a minimum temperature of approximately −10° C. or lower, a maximumtemperature of approximately 70° C. or higher, and an optical anisotropyin the range of approximately 0.06 to approximately 0.18. The devicecontaining the composition has a large voltage holding ratio. Thecomposition is suitable for an AM device. The composition is suitableespecially for an AM device having a transmission type. The compositionhaving an optical anisotropy in the range of approximately 0.05 toapproximately 0.25, and further in the range of approximately 0.04 toapproximately 0.30 may be prepared by regulating ratios of the componentcompounds or by mixing with any other liquid crystal compound. Thecomposition can be used as a composition having a nematic phase and asan optically active composition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Itis especially desirable to use the composition for the AM device havingthe TN, OCB or IPS mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device having the transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

A composition and a compound were a subject for measurement in order toevaluate the characteristics of the composition and the compound thatwas included in the composition. When the subject for measurement was acomposition, the composition itself was measured as a sample, and thevalue obtained was described here. When the subject for measurement wasa compound, a sample for measurement was prepared by mixing the compound(15% by weight) with mother liquid crystals (85% by weight).Characteristic values of the compound were calculated from valuesobtained by measurement, according to a method of extrapolation. Thatis: (extrapolated value)=[(measured value of a sample formeasurement)−0.85×(measured value of mother liquid crystals)]/0.15. Whena smectic phase (or crystals) separated out at this ratio at 25° C., theratio of the compound to the mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight) and (1% by weight/99% by weight). Values of the maximumtemperature, the optical anisotropy, the viscosity and the dielectricanisotropy with regard to the compound were obtained by theextrapolation.

The components of the mother liquid crystals were as follows. The ratioof each component is expressed in a percentage by weight.

Characteristics were measured according to the following methods. Mostmethods are described in the Standards of Electronic IndustriesAssociation of Japan, EIAJ-ED-2521 A or those with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Temperaturewas measured when part of the sample began to change from a nematicphase to an isotropic liquid. A higher limit of the temperature range ofa nematic phase may occasionally be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample remained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as ≦−20° C. Alower limit of the temperature range of a nematic phase may occasionallybe abbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s):Measurement was carried out according to the method described in M.Imai, et al., Molecular Crystals and Liquid Crystals, Vol. 259, 37(1995). A sample was poured into a TN device having the twist angle of 0degrees and the distance between two glass substrates (cell gap) of 5micrometers. The TN device was applied with a voltage stepwise with anincrement of 0.5 volt in the range of 16 to 19.5 volts. After a periodof 0.2 second without applied voltage, applied voltage was repeatedunder the conditions of only one rectangular wave (rectangular pulse;0.2 second) and no voltage applied (2 seconds). The peak current and thepeak time of the transient current generated by the voltage applied weremeasured. The value of rotational viscosity was obtained from themeasured values and the calculating equation (8) in page 40 of the paperpresented by M. Imai, et al. The value of dielectric anisotropynecessary for this calculation was obtained by use of the device thathad been used for the measurement of rotational viscosity, according tothe method that will be described below.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, on irradiation with light at awavelength of 589 nanometers. The surface of the main prism was rubbedin one direction, and then a sample was dropped on the main prism. Arefractive index (n∥) was measured when the direction of polarized lightwas parallel to that of the rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thatof the rubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at ° C.): A sample was poured into aTN device having the distance between two glass plates (cell gap) of 9micrometers and the twist angle of 80 degrees. Sine waves (10 V, 1 kHz)were applied onto the device, and a dielectric constant (∈∥) in a majoraxis direction of liquid crystal molecules was measured after 2 seconds.Sine waves (0.5 V, 1 kHz) were applied onto the device and a dielectricconstant (∈⊥) in a minor axis direction of liquid crystal molecules wasmeasured after 2 seconds. A value of the dielectric anisotropy wascalculated from the equation:

Δ∈=∈∥−∈⊥.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a TN device having a normally white mode, in which thedistance between two glass substrates (cell gap) was about 4.45/An(micrometers) and the twist angle was 80 degrees. Voltage to be appliedonto the device (32 Hz, rectangular waves) was stepwise increased in0.02 V increments from 0 V up to 10 V. During the increase, the devicewas irradiated with light in the perpendicular direction, and the amountof light passing through the device was measured. Avoltage-transmittance curve was prepared, in which the maximum amount oflight corresponded to 100% transmittance and the minimum amount of lightcorresponded to 0% transmittance. The threshold voltage was voltage at90% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweentwo glass substrates (cell gap) was 5 micrometers. A sample was pouredinto the device, and then the device was sealed with an adhesive curableon irradiation with ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and the area A between a voltage curve and a horizontal axis in a unitcycle was obtained. The area B was an area without the decrease. Thevoltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweentwo glass substrates (cell gap) was 5 micrometers. A sample was pouredinto the device, and then the device was sealed with an adhesive curableon irradiation with ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeterand the area A between a voltage curve and a horizontal axis in a unitcycle was obtained. The area B was an area without the decrease. Thevoltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiation of a sample with ultraviolet light,evaluating the stability to ultraviolet light. A composition having alarge VHR-3 has a high stability to ultraviolet light. A TN device usedfor measurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into the device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. The value of VHR-3 is preferably 90% or more, and morepreferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the voltage holding ratio was measured,evaluating the stability to heat. A composition having a large VHR-4 hasa high stability to heat. In the measurement of VHR-4, a decreasingvoltage was measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a TN device having anormally white mode, in which the cell gap between two glass substrateswas 5.0 micrometers, and the twist angle was 80 degrees. Rectangularwaves (60 Hz, 10 V, 0.5 second) were applied to the device. The devicewas simultaneously irradiated with light in the perpendicular direction,and the amount of light passing through the device was measured. Themaximum amount of light corresponded to 100% transmittance, and theminimum amount of light corresponded to 0% transmittance. Rise time (τr;millisecond) was the time required for a change from 90% to 10%transmittance. Fall time (τf; millisecond) was the time required for achange from 10% to 90% transmittance. The response time was the sum ofthe rise time and the fall time thus obtained.

Specific resistance (ρ; measured at 25° C.; Ω cm): A sample of 1.0milliliter was poured into a vessel equipped with electrodes. DC voltage(10V) was applied to the vessel, and the DC current was measured after10 seconds. The specific resistance was calculated according to thefollowing equation. (specific resistance)=[(voltage)×(electric capacityof vessel)]/[(DC current)×(dielectric constant in a vacuum)].

Gas chromatographic analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The evaporator and the detector (FID)were set to 280° C. and 300° C., respectively. A capillary column DB-1(length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer,dimethylpolysiloxane as the stationary phase, non-polar) made by AgilentTechnologies, Inc. was used for the separation of component compounds.After the column had been kept at 200° C. for 2 minutes, it was furtherheated to 280° C. at the rate of 5° C. per minute. A sample wasdissolved in acetone (0.1% by weight), and 1 microliter of the solutionwas injected into the evaporator. A recorder used was a Model C-R5AChromatopac Integrator made by Shimadzu Corporation or its equivalent. Agas chromatogram obtained showed the retention time of peaks and thepeak areas corresponding to the component compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (50 meters,bore 0.25 millimeter, film thickness 0.25 micrometer) made by ShimadzuCorporation may also be used for the purpose of avoiding an overlap ofpeaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (in moles) of theliquid crystal compounds. When the capillary columns described above areused, the correction coefficient of respective liquid crystal compoundsmay be regarded as one. Accordingly, the ratio (% by weight) of theliquid crystal compound can be calculated from the ratio of peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed as symbolsaccording to the definition in the following Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto the symbolized compound in Example corresponds to a compound number.The symbol (-) means any other liquid crystal compound. Ratios(percentage) of liquid crystal compounds mean percentages by weight (%by weight) based on the total weight of the liquid crystal composition.The liquid crystal composition further includes an impurity. Last,characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols R—(A1)—Z1— . . .—Zn—(An)—R′ 1) Left Terminal Group R— Symbol C_(n)H_(2n+1)— n—C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)CH═CH—C_(n)H_(2n)— mVn— CH₂═CH—C₂H₄—CH═CH—C₂H₄— V2V2—CF₂═CH— VFF— CF₂═CH—(CH₂)₂— VFF2— 2) Right Terminal Group —R′ Symbol—C_(n)H_(2n+1) —n —OC_(n)H_(2n+1) —On —F —F —Cl —CL —OCF₃ —OCF3—OCF₂CFHCF₃ —OCF2CFHCF3 —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ —nV —CH═CF₂ —VFF —CF₃ —CF3 3) Bonding Group —Z_(n)—Symbol —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X 4) Ring Structure—A_(n)— Symbol

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

Py

G 5) Example of Description Example 1. 3-HB(F)HH-5

Example 2. 5-BB(F)B(F,F)XB(F,F)-F

Example 3. 2-BB(F)B-2V

Example 4. 4-HHB—CL

Comparative Example 1

Example 62 was selected from compositions disclosed in JP 2002-533526 A(the patent document No. 1) for comparison. The basis for the selectionwas because, among compositions including the compound (1-1) and thecompound (1-2), the composition had a high NI and a low thresholdvoltage, The composition had the following components andcharacteristics. Values of characteristics were obtained by measurementsaccording to the methods described above.

2-HB(F)HH-3 (1-1) 5% 2-HB(F)HH-5 (1-1) 5% 2-HB(2F)HH-3 (1-2) 4%5-HB(2F)HH-3 (1-2) 3% 3-HH-5 (3-1) 5% 5-HH-V (3-1) 9% 3-HH-O1 (3-1) 9%5-HH-O1 (3-1) 10% 2-HHB(F,F)-F (4-1) 8% 2-HGB(F,F)-F (4-5) 8%3-HGB(F,F)-F (4-5) 10% 4-HHEH-3 (5-2) 3% 3-HH1OH-3 (5-4) 3% 4-HH1OH-3(5-4) 5% 3-HH1OH-5 (5-4) 2% 3-HH-CF3 (—) 3% 5-HH-CF3 (—) 8%

NI=96.2° C.; Δn=0.061; Δ∈=3.4; Vth=2.04 V; γ1=163 mPa·s; Tc≦−10° C.

Comment: Data on comparative example 1 described in the patent documentNo. 1 are as follows.

NI=96.0° C.; Tc≦−40° C.; Δn=0.0615; Vth=2.25 V.

Example 1

3-HB(F)HH-5 (1-1) 10% 3-HHXB(F,F)-F (2-2-1) 11% 3-BB(F,F)XB(F,F)-F(2-2-2) 16% 3-HH-V (3-1) 14% 1-HHB(F,F)-F (4-1) 5% 2-HHB(F,F)-F (4-1) 5%3-HHB(F,F)-F (4-1) 8% 3-HBB(F,F)-F (4-4) 13% V-HHB-1 (5-1) 5% V2-HHB-1(5-1) 4% 3-HHEBH-3 (5-9) 3% 3-HHEBH-4 (5-9) 3% 3-HHEBH-5 (5-9) 3%

NI=112.0° C.; Tc≦−40° C.; Δn=0.098; Δ∈=7.6; Vth=1.62 V; η=20.8 mPa·s;γ1=111 mPa·s; VHR-1=99.4%; VHR-2=99.1%.

Example 2

3-HB(F)HH-5 (1-1) 10% 5-HXB(F,F)-F (2-1-1) 11% 1-HHXB(F,F)-F (2-2-1) 6%3-HHXB(F,F)-F (2-2-1) 20% 3-HH-4 (3-1) 11% 1-HHB(F,F)-F (4-1) 5%2-HHB(F,F)-F (4-1) 6% 3-HHB(F,F)-F (4-1) 10% 3-GHB(F,F)-F (4-6) 3%5-GHB(F,F)-F (4-6) 4% 3-HHEH-3 (5-2) 5% 3-HHEB-F (5-3) 5% 5-HHEB-F (5-3)4%

NI=97.9° C.; Tc≦−40° C.; Δn=0.068; Δ∈=6.9; Vth=1.38 V; η=19.7 mPa·s;γ1=145 mPa·s.

Example 3

3-HB(F)HH-2 (1-1) 3% 3-HB(F)HH-5 (1-1) 8% 5-HB(2F)HH-3 (1-2) 4%1-HHXB(F,F)-F (2-2-1) 8% 3-HHXB(F,F)-F (2-2-1) 16% 3-BB(F,F)XB(F,F)-F(2-2-2) 8% 3-HH-5 (3-1) 14% 3-HB-O2 (3-2) 5% 7-HB-1 (3-2) 3% 1-BB-2V(3-3) 2% 1-HHB(F,F)-F (4-1) 4% 2-HHB(F,F)-F (4-1) 6% 3-HHB(F,F)-F (4-1)10% V-HHB-1 (5-1) 9%

NI=101.8° C.; Tc≦−30° C.; Δn=0.086; Δ∈=5.4; Vth=1.84 V; η=21.3 mPa·s;γ1=115 mPa·s; VHR-1=99.5%; VHR-2=99.3%.

Example 4

2-HB(F)HH-3 (1-1) 2% 3-HB(F)HH-5 (1-1) 5% 3-HHXB(F,F)-F (2-2-1) 14%3-BB(F,F)XB(F,F)-F (2-2-2) 16% 4-BB(F)B(F,F)XB(F,F)-F (2-3-1) 5% 3-HH-V(3-1) 27% 3-HH-V1 (3-1) 10% 2-HHBB(F,F)-F (4-9) 4% 4-HHBB(F,F)-F (4-9)4% 3-HHB-F (5-1) 2% V-HHB-1 (5-1) 11%

NI=97.2° C.; Tc≦−30° C.; Δn=0.095; Δ∈=6.3; Vth=1.76 V; η=13.2 mPa·s;γ1=71 mPa·s; VHR-1=99.5%; VHR-2=99.3%.

Example 5

3-HB(F)HH-2 (1-1) 8% 3-HB(F)HH-5 (1-1) 12% 3-HHXB(F,F)-F (2-2-1) 14%3-BB(F,F)XB(F,F)-F (2-2-2) 16% 3-BB(F)B(F,F)XB(F,F)-F (2-3-1) 2%4-BB(F)B(F,F)XB(F,F)-F (2-3-1) 7% 5-BB(F)B(F,F)XB(F,F)-F (2-3-1) 4%3-HH-V (3-1) 27% 3-HH-V1 (3-1) 10%

NI=103.5° C.; Tc≦−30° C.; Δn=0.099; Δ∈=7.8; Vth=1.62 V; η=20.2 mPa·s;γ1=112 mPa·s.

Example 6

3-HB(F)HH-5 (1-1) 5% 3-HB(F)HH-V (1-1) 2% 3-HB(2F)HH-3 (1-2) 2%3-BB(F,F)XB(F,F)-F (2-2-2) 18% 3-HH-V (3-1) 9% 3-HH-V1 (3-1) 3% 3-HB-CL(3-2) 5% 3-HBB(F,F)-F (4-4) 27% 2-HHBB(F,F)-F (4-9) 3% 3-HHBB(F,F)-F(4-9) 3% 4-HHBB(F,F)-F (4-9) 3% V-HHB-1 (5-1) 12% 2-BB(F)B-3 (5-6) 8%

NI=98.1° C.; Tc≦−40° C.; Δn=0.130; Δ∈=7.9; Vth=1.82 V; η=21.7 mPa·s;γ1=127 mPa·s.

Example 7

3-HB(F)HH-5 (1-1) 5% 5-HB(2F)HH-V (1-2) 2% 1-HHXB(F,F)-F (2-2-1) 10%3-HHXB(F,F)-F (2-2-1) 15% 5-HH-V (3-1) 6% 3-HH-O1 (3-1) 16% 5-HH-O1(3-1) 6% 5-HB-O2 (3-2) 5% 3-HHB(F,F)-F (4-1) 4% 3-H2HB(F,F)-F (4-2) 3%5-HH2B(F,F)-F (4-3) 3% 3-HBB(F,F)-F (4-4) 6% 3-HHBB(F,F)-F (4-9) 3%3-HHB-1 (5-1) 2% V-HHB-1 (5-1) 2% 3-HHEH-3 (5-2) 3% 3-HHEH-5 (5-2) 3%4-HHEH-3 (5-2) 3% 4-HHEH-5 (5-2) 3%

NI=96.9° C.; Tc≦−40° C.; Δn=0.071; Δ∈=3.5; Vth=1.93 V; η=20.7 mPa·s;VHR-1=99.5%; VHR-2=99.1%.

Example 8

2-HB(F)HH-5 (1-1) 2% 3-HB(F)HH-5 (1-1) 3% 2-HB(2F)HH-3 (1-2) 2%3-HHXB(F,F)-F (2-2-1) 17% 3-BB(F,F)XB(F,F)-F (2-2-2) 13% VFF-HH-3 (3-1)25% 3-HBB(F,F)-F (4-4) 14% 2-HHEB(F,F)-F (4-8) 3% 3-HHEB(F,F)-F (4-8) 3%4-HHEB(F,F)-F (4-8) 3% 5-HHEB(F,F)-F (4-8) 3% 2-HHBB(F,F)-F (4-9) 3%3-HHBB(F,F)-F (4-9) 2% 5-HBB(F)B-2 (5-8) 4% 5-HBB(F)B-3 (5-8) 3%

NI=96.5° C.; Tc≦−30° C.; Δn=0.101; Δ∈=7.9; Vth=1.49 V; η=18.9 mPa·s;γ1=104 mPa·s.

Example 9

3-HB(F)HH-2 (1-1) 3% 3-HB(F)HH-5 (1-1) 3% 1-HHXB(F,F)-F (2-2-1) 9%3-HHXB(F,F)-F (2-2-1) 19% 3-HH-V1 (3-1) 7% VFF-HH-3 (3-1) 12% 3-HB-CL(3-2) 6% 3-HHB(F,F)-F (4-1) 9% 3-HGB(F,F)-F (4-5) 5% 5-GHB(F,F)-F (4-6)8% 3-H2GB(F,F)-F (4-7) 2% VFF-HHB-1 (5-1) 6% VFF2-HHB-1 (5-1) 3%3-HHEH-3 (5-2) 2% 3-HH1OH-5 (5-4) 2% 5-HH1OH-3 (5-4) 2% 1O1-HBBH-4 (—)2%

NI=98.0° C.; Tc≦−40° C.; Δn=0.071; Δ∈=5.9; Vth=1.53 V; η=18.3 mPa·s;γ1=123 mPa·s.

Example 10

3-HB(F)HH-5 (1-1) 7% 3-BB(F,F)XB(F,F)-F (2-2-2) 14%3-BB(F)B(F,F)XB(F,F)-F (2-3-1) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-3-1) 9%4-HBBXB(F,F)-F (2-3-2) 4% 4-HH-V (3-1) 12% 3-HBB(F,F)-F (4-4) 27%2-HHBB(F,F)-F (4-9) 4% 3-HHBB(F,F)-F (4-9) 4% 4-HHBB(F,F)-F (4-9) 4%3-HBB-F (5-5) 2% V2-BB(F)B-1 (5-6) 5% V2-BB(F)B-2 (5-6) 5%

NI=104.5° C.; Tc≦−40° C.; Δn=0.150; Δ∈=12.6; Vth=1.46 V; η=39.7 mPa·s;γ1=151 mPa·s.

Example 11

3-HB(F)HH-2 (1-1) 3% 3-HB(F)HH-5 (1-1) 10% 1-HHXB(F,F)-F (2-2-1) 8%3-HHXB(F,F)-F (2-2-1) 16% 3-BB(F,F)XB(F,F)-F (2-2-2) 4% 3-HH-4 (3-1) 4%3-HH-5 (3-1) 10% 3-HB-O2 (3-2) 8% 5-HB-O2 (3-2) 4% 1-HHB(F,F)-F (4-1) 5%2-HHB(F,F)-F (4-1) 5% 3-HHB(F,F)-F (4-1) 10% 3-HHB-1 (5-1) 9% 5-HH-OCF3(—) 4%

NI-98.3° C.; Tc≦−30° C.; Δn=0.087; Δ∈=4.5; Vth=1.99 V; η=19.9 mPa·s;γ1=107 mPa·s.

Example 12

5-HB(F)HH-V1 (1-1) 2% 3-HB(F)HH-O1 (1-1) 2% 5-HB(F)HH-O3 (1-1) 2%2O-HB(F)HH-V (1-1) 2% V-HB(F)HH-5 (1-1) 2% 3-HHXB(F,F)-F (2-2-1) 12%3-BB(F,F)XB(F,F)-F (2-2-2) 8% V2-BB(F,F)XB(F,F)-F (2-2-2) 7% 2-HH-3(3-1) 4% 3-HH-V (3-1) 10% 3-HB-O2 (3-2) 5% 2-HHB(F,F)-F (4-1) 3%3-HHB(F,F)-F (4-1) 8% V-HHB(F,F)-F (4-1) 5% 3-HBB(F,F)-F (4-4) 7%3-BB(F)B(F,F)-F  (4-13) 3% 3-HHB-1 (5-1) 4% 3-HHB-O1 (5-1) 5% 3-HHB-CL(5-1) 3% 3-HHEBH-4 (5-9) 3% 3-HHEBH-5 (5-9) 3%

NI=99.0° C.; Tc≦−30° C.; Δn=0.97; Δ∈=7.2; Vth=1.69 V; η=20.5 mPa·s;γ1=108 mPa·s.

The compositions in Examples 1 to 12 had a high maximum temperature of anematic phase, a large dielectric anisotropy and a small thresholdvoltage in comparison with those in Comparative Example 1. Thus, theliquid crystal composition of the invention was so much superior incharacteristics to that described in the patent document No. 1.

APPLICABILITY TO THE INDUSTRY

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large dielectric anisotropy,a large specific resistance, a high stability to ultraviolet light and ahigh stability to heat. Since a liquid crystal display device thatcontains the composition provides an AM device having a short responsetime, a large voltage holding ratio, a large contrast ratio, a longservice life and so forth, it can be used for a liquid crystalprojector, a liquid crystal television and so forth.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal composition that has a nematic phase and comprisesthree components, wherein a first component is at least one compoundselected from the group of compounds represented by formula (1), asecond component is at least one compound selected from the group ofcompounds represented by formula (2), and a third component is at leastone compound selected from the group of compounds represented by formula(3):

wherein R¹, R² and R³ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁵ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine; one of X¹ and X² is fluorine andthe other is hydrogen; the ring A and the ring B are each independently

the ring C and the ring D are each independently

and m is 0, 1 or
 2. 2. The liquid crystal composition according to claim1, wherein the first component is at least one compound selected fromthe group of compounds represented by formula (1-1):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.
 3. Theliquid crystal composition according to claim 1, wherein the secondcomponent is at least one compound selected from the group of compoundsrepresented by formula (2-1-1), formula (2-2-1), formula (2-2-2),formula (2-3-1) and formula (2-3-2):

wherein R³ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 4. The liquid crystalcomposition according to claim 1, wherein the third component is atleast one compound selected from the group of compounds represented byformula (3-1), formula (3-2) and formula (3-3)

wherein R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁵ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine.
 5. The liquid crystal compositionaccording to claim 4, wherein the third component is at least onecompound selected from the group of compounds represented by formula(3-1).
 6. The liquid crystal composition according to claim 1, whereinthe ratio of the first component is in the range of approximately 5% toapproximately 30% by weight, the ratio of the second component is in therange of approximately 5% to approximately 50% by weight, and the ratioof the third component is in the range of approximately 5% toapproximately 50% by weight, based on the total weight of the liquidcrystal composition.
 7. The liquid crystal composition according toclaim 1, further comprising at least one compound selected from thegroup of compounds represented by formula (4) as a fourth component:

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; Z¹ and Z² are eachindependently a single bond, ethylene or carbonyloxy; the ring E and thering F are each independently

and n is 1 or
 2. 8. The liquid crystal composition according to claim 7,wherein the fourth component is at least one compound selected from thegroup of compounds represented by formula (4-1) to formula (4-9):

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 9. The liquid crystalcomposition according to claim 1, further comprising at least onecompound selected from the group of compounds represented by formula (5)as a fifth component:

wherein R⁷ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁸ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine; Z³ and Z⁴ are each independently asingle bond, ethylene, carbonyloxy, methyleneoxy or oxymethylene; thering G, the ring H and the ring I are each independently

and p is 1 or
 2. 10. The liquid crystal composition according to claim9, wherein the fifth component is at least one compound selected fromthe group of compounds represented by formula (5-1) to formula (5-9):

wherein, R⁷ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁸ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, fluorine or chlorine.
 11. The liquid crystal compositionaccording to claim 1, wherein the ratio of the first component is in therange of approximately 5% to approximately 30% by weight, the ratio ofthe second component is in the range of approximately 15% toapproximately 45% by weight, the ratio of the third component is in therange of approximately 10% to approximately 40% by weight, the ratio ofthe fourth component is in the range of 0% to approximately 50% byweight, and the ratio of the fifth component is in the range of 0% toapproximately 30% by weight, based on the total weight of the liquidcrystal composition.
 12. A liquid crystal display device comprising theliquid crystal composition according to claim
 1. 13. The liquid crystaldisplay device according to claim 12, wherein an operating mode of theliquid crystal display device is a TN mode, an ECB mode, an OCB mode, anIPS mode or a PSA mode, and a driving mode of the liquid crystal displaydevice is an active matrix mode.